68
48
<refname><command>&COMMANDNAME;</command></refname>
70
Sends encrypted passwords to authenticated Mandos clients
50
Gives encrypted passwords to authenticated Mandos clients
76
56
<command>&COMMANDNAME;</command>
77
<arg choice='opt'>--interface<arg choice='plain'>IF</arg></arg>
78
<arg choice='opt'>--address<arg choice='plain'>ADDRESS</arg></arg>
79
<arg choice='opt'>--port<arg choice='plain'>PORT</arg></arg>
80
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
81
<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
82
<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
83
<arg choice='opt'>--debug</arg>
86
<command>&COMMANDNAME;</command>
87
<arg choice='opt'>-i<arg choice='plain'>IF</arg></arg>
88
<arg choice='opt'>-a<arg choice='plain'>ADDRESS</arg></arg>
89
<arg choice='opt'>-p<arg choice='plain'>PORT</arg></arg>
90
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
91
<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
92
<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
93
<arg choice='opt'>--debug</arg>
96
<command>&COMMANDNAME;</command>
97
<arg choice='plain'>--help</arg>
100
<command>&COMMANDNAME;</command>
101
<arg choice='plain'>--version</arg>
104
<command>&COMMANDNAME;</command>
105
<arg choice='plain'>--check</arg>
58
<arg choice="plain"><option>--interface
59
<replaceable>NAME</replaceable></option></arg>
60
<arg choice="plain"><option>-i
61
<replaceable>NAME</replaceable></option></arg>
65
<arg choice="plain"><option>--address
66
<replaceable>ADDRESS</replaceable></option></arg>
67
<arg choice="plain"><option>-a
68
<replaceable>ADDRESS</replaceable></option></arg>
72
<arg choice="plain"><option>--port
73
<replaceable>PORT</replaceable></option></arg>
74
<arg choice="plain"><option>-p
75
<replaceable>PORT</replaceable></option></arg>
78
<arg><option>--priority
79
<replaceable>PRIORITY</replaceable></option></arg>
81
<arg><option>--servicename
82
<replaceable>NAME</replaceable></option></arg>
84
<arg><option>--configdir
85
<replaceable>DIRECTORY</replaceable></option></arg>
87
<arg><option>--debug</option></arg>
89
<arg><option>--no-dbus</option></arg>
91
<arg><option>--no-ipv6</option></arg>
94
<command>&COMMANDNAME;</command>
96
<arg choice="plain"><option>--help</option></arg>
97
<arg choice="plain"><option>-h</option></arg>
101
<command>&COMMANDNAME;</command>
102
<arg choice="plain"><option>--version</option></arg>
105
<command>&COMMANDNAME;</command>
106
<arg choice="plain"><option>--check</option></arg>
107
108
</refsynopsisdiv>
109
110
<refsect1 id="description">
110
111
<title>DESCRIPTION</title>
112
113
<command>&COMMANDNAME;</command> is a server daemon which
113
114
handles incoming request for passwords for a pre-defined list of
114
115
client host computers. The Mandos server uses Zeroconf to
115
announce itself on the local network, and uses GnuTLS to
116
communicate securely with and to authenticate the clients.
117
Mandos uses IPv6 link-local addresses, since the clients are
118
assumed to not have any other addresses configured yet. Any
119
authenticated client is then given the pre-encrypted password
120
for that specific client.
116
announce itself on the local network, and uses TLS to
117
communicate securely with and to authenticate the clients. The
118
Mandos server uses IPv6 to allow Mandos clients to use IPv6
119
link-local addresses, since the clients will probably not have
120
any other addresses configured (see <xref linkend="overview"/>).
121
Any authenticated client is then given the stored pre-encrypted
122
password for that specific client.
125
126
<refsect1 id="purpose">
126
127
<title>PURPOSE</title>
129
129
The purpose of this is to enable <emphasis>remote and unattended
130
rebooting</emphasis> of any client host computer with an
131
<emphasis>encrypted root file system</emphasis>. The client
132
host computer should start a Mandos client in the initial RAM
133
disk environment, the Mandos client program communicates with
134
this server program to get an encrypted password, which is then
135
decrypted and used to unlock the encrypted root file system.
136
The client host computer can then continue its boot sequence
130
rebooting</emphasis> of client host computer with an
131
<emphasis>encrypted root file system</emphasis>. See <xref
132
linkend="overview"/> for details.
142
136
<refsect1 id="options">
143
137
<title>OPTIONS</title>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
140
<term><option>--help</option></term>
141
<term><option>-h</option></term>
150
144
Show a help message and exit
156
<term><literal>-i</literal>, <literal>--interface <replaceable>
157
IF</replaceable></literal></term>
160
Only announce the server and listen to requests on network
161
interface <replaceable>IF</replaceable>. Default is to
162
use all available interfaces.
168
<term><literal>-a</literal>, <literal>--address <replaceable>
169
ADDRESS</replaceable></literal></term>
172
If this option is used, the server will only listen to a
173
specific address. This must currently be an IPv6 address;
174
an IPv4 address can be specified using the
175
"<literal>::FFFF:192.0.2.3</literal>" syntax. Also, if a
176
link-local address is specified, an interface should be
177
set, since a link-local address is only valid on a single
178
interface. By default, the server will listen to all
185
<term><literal>-p</literal>, <literal>--port <replaceable>
186
PORT</replaceable></literal></term>
189
If this option is used, the server to bind to that
190
port. By default, the server will listen to an arbitrary
191
port given by the operating system.
197
<term><literal>--check</literal></term>
200
Run the server's self-tests. This includes any unit
150
<term><option>--interface</option>
151
<replaceable>NAME</replaceable></term>
152
<term><option>-i</option>
153
<replaceable>NAME</replaceable></term>
155
<xi:include href="mandos-options.xml" xpointer="interface"/>
160
<term><option>--address
161
<replaceable>ADDRESS</replaceable></option></term>
163
<replaceable>ADDRESS</replaceable></option></term>
165
<xi:include href="mandos-options.xml" xpointer="address"/>
171
<replaceable>PORT</replaceable></option></term>
173
<replaceable>PORT</replaceable></option></term>
175
<xi:include href="mandos-options.xml" xpointer="port"/>
180
<term><option>--check</option></term>
183
Run the server’s self-tests. This includes any unit
207
<term><literal>--debug</literal></term>
210
If the server is run in debug mode, it will run in the
211
foreground and print a lot of debugging information. The
212
default is <emphasis>not</emphasis> to run in debug mode.
218
<term><literal>--priority <replaceable>
219
PRIORITY</replaceable></literal></term>
222
GnuTLS priority string for the TLS handshake with the
224
<citerefentry><refentrytitle>gnutls_priority_init
225
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
226
for the syntax. The default is
227
"<literal>SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP</literal>".
228
<emphasis>Warning</emphasis>: changing this may make the
229
TLS handshake fail, making communication with clients
236
<term><literal>--servicename <replaceable>NAME</replaceable>
240
Zeroconf service name. The default is
241
"<literal>Mandos</literal>". You only need to change this
242
if you for some reason want to run more than one server on
243
the same <emphasis>host</emphasis>. If there are name
244
collisions on the same <emphasis>network</emphasis>, the
245
new server will automatically rename itself to "Mandos
252
<term><literal>--configdir <replaceable>DIR</replaceable>
190
<term><option>--debug</option></term>
192
<xi:include href="mandos-options.xml" xpointer="debug"/>
197
<term><option>--priority <replaceable>
198
PRIORITY</replaceable></option></term>
200
<xi:include href="mandos-options.xml" xpointer="priority"/>
205
<term><option>--servicename
206
<replaceable>NAME</replaceable></option></term>
208
<xi:include href="mandos-options.xml"
209
xpointer="servicename"/>
214
<term><option>--configdir
215
<replaceable>DIRECTORY</replaceable></option></term>
256
218
Directory to search for configuration files. Default is
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
219
<quote><literal>/etc/mandos</literal></quote>. See
220
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
259
221
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
260
222
<refentrytitle>mandos-clients.conf</refentrytitle>
261
223
<manvolnum>5</manvolnum></citerefentry>.
267
<term><literal>--version</literal></term>
229
<term><option>--version</option></term>
270
232
Prints the program version and exit.
238
<term><option>--no-dbus</option></term>
240
<xi:include href="mandos-options.xml" xpointer="dbus"/>
242
See also <xref linkend="dbus_interface"/>.
248
<term><option>--no-ipv6</option></term>
250
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
256
<refsect1 id="overview">
257
<title>OVERVIEW</title>
258
<xi:include href="overview.xml"/>
260
This program is the server part. It is a normal server program
261
and will run in a normal system environment, not in an initial
262
<acronym>RAM</acronym> disk environment.
277
266
<refsect1 id="protocol">
278
267
<title>NETWORK PROTOCOL</title>
280
269
The Mandos server announces itself as a Zeroconf service of type
281
"<literal>_mandos._tcp</literal>". The Mandos client connects
282
to the announced address and port, and sends a line of text
283
where the first whitespace-separated field is the protocol
284
version, which currently is "<literal>1</literal>". The client
285
and server then start a TLS protocol handshake with a slight
286
quirk: the Mandos server program acts as a TLS "client" while
287
the connecting Mandos client acts as a TLS "server". The Mandos
288
client must supply an OpenPGP certificate, and the fingerprint
289
of this certificate is used by the Mandos server to look up (in
290
a list read from a file at start time) which binary blob to give
291
the client. No other authentication or authorization is done by
270
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
271
client connects to the announced address and port, and sends a
272
line of text where the first whitespace-separated field is the
273
protocol version, which currently is
274
<quote><literal>1</literal></quote>. The client and server then
275
start a TLS protocol handshake with a slight quirk: the Mandos
276
server program acts as a TLS <quote>client</quote> while the
277
connecting Mandos client acts as a TLS <quote>server</quote>.
278
The Mandos client must supply an OpenPGP certificate, and the
279
fingerprint of this certificate is used by the Mandos server to
280
look up (in a list read from <filename>clients.conf</filename>
281
at start time) which binary blob to give the client. No other
282
authentication or authorization is done by the server.
294
<informaltable><tgroup cols="3"><thead>
285
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
287
<entry>Mandos Client</entry>
297
288
<entry>Direction</entry>
347
365
critical error is encountered.
369
<refsect1 id="environment">
370
<title>ENVIRONMENT</title>
373
<term><envar>PATH</envar></term>
376
To start the configured checker (see <xref
377
linkend="checking"/>), the server uses
378
<filename>/bin/sh</filename>, which in turn uses
379
<varname>PATH</varname> to search for matching commands if
380
an absolute path is not given. See <citerefentry>
381
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
389
<refsect1 id="files">
352
390
<title>FILES</title>
356
<filename>/etc/mandos/mandos.conf</filename> See <citerefentry>
357
<refentrytitle>mandos.conf</refentrytitle>
358
<manvolnum>5</manvolnum></citerefentry>.
361
<filename>/etc/mandos/clients.conf</filename> See <citerefentry>
392
Use the <option>--configdir</option> option to change where
393
<command>&COMMANDNAME;</command> looks for its configurations
394
files. The default file names are listed here.
398
<term><filename>/etc/mandos/mandos.conf</filename></term>
401
Server-global settings. See
402
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
403
<manvolnum>5</manvolnum></citerefentry> for details.
408
<term><filename>/etc/mandos/clients.conf</filename></term>
411
List of clients and client-specific settings. See
412
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
413
<manvolnum>5</manvolnum></citerefentry> for details.
418
<term><filename>/var/run/mandos.pid</filename></term>
421
The file containing the process id of
422
<command>&COMMANDNAME;</command>.
427
<term><filename>/dev/log</filename></term>
430
The Unix domain socket to where local syslog messages are
436
<term><filename>/bin/sh</filename></term>
439
This is used to start the configured checker command for
440
each client. See <citerefentry>
362
441
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
442
<manvolnum>5</manvolnum></citerefentry> for details.
372
449
<refsect1 id="bugs">
373
450
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
452
This server might, on especially fatal errors, emit a Python
453
backtrace. This could be considered a feature.
456
Currently, if a client is disabled due to having timed out, the
457
server does not record this fact onto permanent storage. This
458
has some security implications, see <xref linkend="clients"/>.
461
There is no fine-grained control over logging and debug output.
464
Debug mode is conflated with running in the foreground.
467
The console log messages do not show a time stamp.
470
This server does not check the expire time of clients’ OpenPGP
475
<refsect1 id="example">
476
<title>EXAMPLE</title>
479
Normal invocation needs no options:
482
<userinput>&COMMANDNAME;</userinput>
487
Run the server in debug mode, read configuration files from
488
the <filename>~/mandos</filename> directory, and use the
489
Zeroconf service name <quote>Test</quote> to not collide with
490
any other official Mandos server on this host:
494
<!-- do not wrap this line -->
495
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
501
Run the server normally, but only listen to one interface and
502
only on the link-local address on that interface:
506
<!-- do not wrap this line -->
507
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
384
513
<refsect1 id="security">
385
514
<title>SECURITY</title>
515
<refsect2 id="server">
516
<title>SERVER</title>
518
Running this <command>&COMMANDNAME;</command> server program
519
should not in itself present any security risk to the host
520
computer running it. The program switches to a non-root user
524
<refsect2 id="clients">
525
<title>CLIENTS</title>
527
The server only gives out its stored data to clients which
528
does have the OpenPGP key of the stored fingerprint. This is
529
guaranteed by the fact that the client sends its OpenPGP
530
public key in the TLS handshake; this ensures it to be
531
genuine. The server computes the fingerprint of the key
532
itself and looks up the fingerprint in its list of
533
clients. The <filename>clients.conf</filename> file (see
534
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
535
<manvolnum>5</manvolnum></citerefentry>)
536
<emphasis>must</emphasis> be made non-readable by anyone
537
except the user starting the server (usually root).
540
As detailed in <xref linkend="checking"/>, the status of all
541
client computers will continually be checked and be assumed
542
compromised if they are gone for too long.
545
If a client is compromised, its downtime should be duly noted
546
by the server which would therefore disable the client. But
547
if the server was ever restarted, it would re-read its client
548
list from its configuration file and again regard all clients
549
therein as enabled, and hence eligible to receive their
550
passwords. Therefore, be careful when restarting servers if
551
it is suspected that a client has, in fact, been compromised
552
by parties who may now be running a fake Mandos client with
553
the keys from the non-encrypted initial <acronym>RAM</acronym>
554
image of the client host. What should be done in that case
555
(if restarting the server program really is necessary) is to
556
stop the server program, edit the configuration file to omit
557
any suspect clients, and restart the server program.
560
For more details on client-side security, see
561
<citerefentry><refentrytitle>mandos-client</refentrytitle>
562
<manvolnum>8mandos</manvolnum></citerefentry>.
390
567
<refsect1 id="see_also">
391
568
<title>SEE ALSO</title>
392
<itemizedlist spacing="compact">
394
<citerefentry><refentrytitle>password-request</refentrytitle>
395
<manvolnum>8mandos</manvolnum></citerefentry>
399
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
400
<manvolnum>8mandos</manvolnum></citerefentry>
404
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
408
<ulink url="http://www.avahi.org/">Avahi</ulink>
413
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
417
<citation>RFC 4880: <citetitle>OpenPGP Message
418
Format</citetitle></citation>
422
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
423
Transport Layer Security</citetitle></citation>
427
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
428
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
429
Unicast Addresses</citation>
571
<refentrytitle>mandos-clients.conf</refentrytitle>
572
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
573
<refentrytitle>mandos.conf</refentrytitle>
574
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
575
<refentrytitle>mandos-client</refentrytitle>
576
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
577
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
583
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
587
Zeroconf is the network protocol standard used by clients
588
for finding this Mandos server on the local network.
594
<ulink url="http://www.avahi.org/">Avahi</ulink>
598
Avahi is the library this server calls to implement
599
Zeroconf service announcements.
605
<ulink url="http://www.gnu.org/software/gnutls/"
610
GnuTLS is the library this server uses to implement TLS for
611
communicating securely with the client, and at the same time
612
confidently get the client’s public OpenPGP key.
618
RFC 4291: <citetitle>IP Version 6 Addressing
619
Architecture</citetitle>
624
<term>Section 2.2: <citetitle>Text Representation of
625
Addresses</citetitle></term>
626
<listitem><para/></listitem>
629
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
630
Address</citetitle></term>
631
<listitem><para/></listitem>
634
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
635
Addresses</citetitle></term>
638
The clients use IPv6 link-local addresses, which are
639
immediately usable since a link-local addresses is
640
automatically assigned to a network interfaces when it
650
RFC 4346: <citetitle>The Transport Layer Security (TLS)
651
Protocol Version 1.1</citetitle>
655
TLS 1.1 is the protocol implemented by GnuTLS.
661
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
665
The data sent to clients is binary encrypted OpenPGP data.
671
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
676
This is implemented by GnuTLS and used by this server so
677
that OpenPGP keys can be used.
684
<!-- Local Variables: -->
685
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
686
<!-- time-stamp-end: "[\"']>" -->
687
<!-- time-stamp-format: "%:y-%02m-%02d" -->